In its natural environment, which is decomposing organic matter and
water, \textit{C.\ elegans} swims and burrows in 3D complex media. Yet
quantitative investigations of \textit{C.\ elegans} locomotion have been
limited to 2D motion. Recently [Phys.\ Fluids 25, 081902 (2013)] we
have provided a quantitative analysis of turning maneuvers of crawling
and swimming nematodes on flat surfaces and in 2D fluid layers. Here,
we follow with the first full 3D description of how \textit{C.\ elegans}
moves in complex 3D environments. We show that the nematode can
explore 3D space by combining 2D turns with roll maneuvers that result
in rotation of the undulation plane around the direction of motion.
Roll motion is achieved by superposing a 2D curvature wave with
nonzero body torsion; 2D turns (within the current undulation plane)
are attained by variation of undulation wave parameters. Our results
indicate that while hydrodynamic interactions reduce angles of 2D
turns, the roll efficiency is significantly enhanced. This
hydrodynamic effect explains the rapid nematode reorientation observed
in 3D swimming.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2016.DFD.H39.5